diabetes mellitus is a major health problem in the United States. If control of hyperglycemia is desirable in this disease, then identification of simple, convenient, and safe methods to achieve this aim, with minimal financial impact, is important. Dietary intervention would seem particularly relevant in this regard. In this proposal we wish to investigate in normal subjects, and a broad range of diabetic subjects: 1) The effects of oral fructose on post-prandial serum glucose, insulin and glucagon levels, and urinary glucose excretion when given acutely in test foods (cake and ice cream): 2) the longer term effects of fructose ingestion when given over a 2 week (hospitalization) and 6 month (outpatient) period of time; 3) the potential effects of fructose as a sweetening agent that will ameliorate the abrupt rise and fall in postprandial serum glucose levels in individuals with documented reactive hypoglycemia, and 4) the metabolic effects of a high fructose diet on in vitro insulin binding and glucose transport in isolated adipocytes as well as overall in vivo insulin effectiveness as assessed by the glucose clamp technique. Our hypothesis is that therapeutically significant reductions in serum glucose and insulin levels will result following acute fructose ingestion. Furthermore, we believe that longer term fructose consumption will not result in adverse side effects and will be superior to the standard diet in maintaining hyperglycemic control in diabetic patients. Lastly, we propose that reactive hypoglycemia will be attenuated following fructose ingestion.